permafrost

The graves were no more than three feet deep, above the permafrost line.

And people have begun to feel the economic permafrost setting in.

It had to be built above the ground in the northern section because of the permafrost.

My main concern is with the warming of the permafrost.

"Can you cut down to the permafrost without hitting the device?"

Send it down into the permafrost, melt our water for us.

Was there a position for a senior investigator out on the permafrost?

Two important parts of this environment are sea ice and permafrost.

"We knew the permafrost would not be here in 20 years because of global warming," he said.

"That can also tell us if there is permafrost beneath the surface, no?"

Permafrost is soil that has been frozen for two or more years.

About a mile ahead, and almost a thousand feet deep in permafrost.

The permafrost softens every summer to about six feet down.

The temperature inside was still cold enough to keep the permafrost frozen.

There is no permafrost in the lower elevations of the park.

Large amounts of permafrost can lead to poor water drainage.

As air and permafrost temperatures change, above ground vegetation also changes.

Continuous permafrost in the north is a serious obstacle to development.

It was found in permafrost, seemingly frozen there for 32,000 years.

Permafrost and tundra cover a large part of the region.

If the permafrost starts to thaw, that process is hard to stop.

The dirt on top of the permafrost is called the active layer.

The permafrost line is within three thousand miles of the equator today.

About half of the second section was built on barely permanent permafrost.

By definition, permafrost is ground that remains frozen for two or more years.